Radiation detector for well-logging tool

Abstract

A radiation detector is used in a well-logging tool for positioning in a wellbore of a geologic formation. The radiation detector includes a photomultiplier housing and a scintillator housing. A housing coupler joins together opposing ends of the photomultiplier housing and scintillator housing. A photomultiplier is contained within the photomultiplier housing and a scintillator body is contained within the scintillator housing. A scintillator window is secured to the housing coupler.

That which is claimed is: 
     
       1. A radiation detector comprising:
 a photomultiplier housing; 
 a scintillator housing; 
 a housing coupler joining opposing ends of said photomultiplier housing and scintillator housing together, wherein the housing coupler forms a hermetic seal that hermetically seals the photomultiplier housing and the scintillator housing; 
 a photomultiplier within said photomultiplier housing; 
 a scintillator body within said scintillator housing; and 
 a scintillator window secured to said housing coupler. 
 
     
     
       2. The radiation detector according to  claim 1  further comprising a brazed joint securing said scintillator window and said housing coupler together. 
     
     
       3. The radiation detector according to  claim 1  wherein said housing coupler defines an enlarged inner diameter relative to said scintillator housing; and wherein said scintillator window has a larger area than an adjacent portion of said scintillator body. 
     
     
       4. The radiation detector according to  claim 1  wherein said scintillator window comprises a first material having a first CTE; and wherein said housing coupler comprises a second material having a second CTE that is within ±20 percent of the first CTE. 
     
     
       5. The radiation detector according to  claim 4  wherein said first material comprises sapphire, and said second material comprises a nickel-cobalt ferrous alloy. 
     
     
       6. The radiation detector according to  claim 1  wherein said photomultiplier comprises a third material having a third CTE; and wherein said scintillator housing comprises a fourth material having a fourth CTE lower than the third CTE. 
     
     
       7. The radiation detector according to  claim 6  wherein said third material comprises stainless steel, and said fourth material comprises titanium. 
     
     
       8. The radiation detector according to  claim 1  wherein said housing coupler defines respective overlapping joints with said photomultiplier housing and said scintillator housing. 
     
     
       9. The radiation detector according to  claim 1  wherein said photomultiplier housing has at least one vent opening therein and at least one plug associated with the at least one vent opening. 
     
     
       10. A well-logging tool for positioning in a wellbore of a geologic formation comprising:
 a well-logging housing and; 
 a radiation detector within the well-logging housing comprising,
 a photomultiplier housing; 
 a scintillator housing; 
 a housing coupler joining opposing ends of said photomultiplier housing and scintillator housing together, wherein the housing coupler forms a hermetic seal that hermetically seals the photomultiplier housing and the scintillator housing; 
 
 a photomultiplier within said photomultiplier housing; 
 a scintillator body within said scintillator housing; 
 a scintillator window within said scintillator housing; and 
 a brazed joint securing said scintillator window and said housing coupler together; 
 said scintillator window comprising a first material having a first CTE; 
 said housing coupler comprising a second material having a second CTE that is within ±20 percent of the first CTE. 
 
     
     
       11. The well-logging tool according to  claim 10  wherein said housing coupler defines an enlarged inner diameter relative to said scintillator housing; and wherein said scintillator window has a larger area than an adjacent portion of said scintillator body. 
     
     
       12. The well-logging tool according to  claim 10  wherein said first material comprises sapphire, and said second material comprises a nickel-cobalt ferrous alloy. 
     
     
       13. The well-logging tool according to  claim 10  wherein said photomultiplier housing comprises a third material having a third coefficient of thermal expansion (CTE); and wherein said scintillator housing comprises a fourth material having a fourth CTE lower than the first CTE. 
     
     
       14. The well-logging tool according to  claim 13  wherein said third material comprises stainless steel, and said fourth material comprises titanium. 
     
     
       15. The well-logging tool according to  claim 10  wherein said housing coupler defines respective overlapping joints with said photomultiplier housing and said scintillator housing. 
     
     
       16. A method for making a radiation detector for a well-logging tool, the method comprising:
 securing a scintillator window and a housing coupler together; and 
 joining opposing ends of a photomultiplier housing and scintillator housing together using the housing coupler, wherein the housing coupler forms a hermetic seal that hermetically seals the photomultiplier housing and the scintillator housing, and with a photomultiplier within the photomultiplier housing, and a scintillator body within the scintillator housing. 
 
     
     
       17. The method according to  claim 16  wherein securing the scintillator window comprises forming a brazed joint to secure the scintillator window and the housing coupler together. 
     
     
       18. The method according to  claim 16  wherein the housing coupler defines an enlarged inner diameter relative to the scintillator housing; and wherein the scintillator window has a larger area than an adjacent portion of the scintillator body. 
     
     
       19. The method according to  claim 16  wherein the scintillator window comprises a first material having a first CTE; and wherein the housing coupler comprises a second material having a second CTE that is within ±20 percent of the first CTE. 
     
     
       20. The method according to  claim 16  wherein the photomultiplier housing comprises a third material having a third CTE; and wherein the scintillator housing comprises a fourth material having a fourth CTE lower than the third CTE.